1 /* 2 * linux/fs/msdos/namei.c 3 * 4 * Written 1992,1993 by Werner Almesberger 5 * Hidden files 1995 by Albert Cahalan <albert@ccs.neu.edu> <adc@coe.neu.edu> 6 * Rewritten for constant inumbers 1999 by Al Viro 7 */ 8 9 #include <linux/module.h> 10 #include <linux/time.h> 11 #include <linux/buffer_head.h> 12 #include "fat.h" 13 14 /* Characters that are undesirable in an MS-DOS file name */ 15 static unsigned char bad_chars[] = "*?<>|\""; 16 static unsigned char bad_if_strict[] = "+=,; "; 17 18 /***** Formats an MS-DOS file name. Rejects invalid names. */ 19 static int msdos_format_name(const unsigned char *name, int len, 20 unsigned char *res, struct fat_mount_options *opts) 21 /* 22 * name is the proposed name, len is its length, res is 23 * the resulting name, opts->name_check is either (r)elaxed, 24 * (n)ormal or (s)trict, opts->dotsOK allows dots at the 25 * beginning of name (for hidden files) 26 */ 27 { 28 unsigned char *walk; 29 unsigned char c; 30 int space; 31 32 if (name[0] == '.') { /* dotfile because . and .. already done */ 33 if (opts->dotsOK) { 34 /* Get rid of dot - test for it elsewhere */ 35 name++; 36 len--; 37 } else 38 return -EINVAL; 39 } 40 /* 41 * disallow names that _really_ start with a dot 42 */ 43 space = 1; 44 c = 0; 45 for (walk = res; len && walk - res < 8; walk++) { 46 c = *name++; 47 len--; 48 if (opts->name_check != 'r' && strchr(bad_chars, c)) 49 return -EINVAL; 50 if (opts->name_check == 's' && strchr(bad_if_strict, c)) 51 return -EINVAL; 52 if (c >= 'A' && c <= 'Z' && opts->name_check == 's') 53 return -EINVAL; 54 if (c < ' ' || c == ':' || c == '\\') 55 return -EINVAL; 56 /* 57 * 0xE5 is legal as a first character, but we must substitute 58 * 0x05 because 0xE5 marks deleted files. Yes, DOS really 59 * does this. 60 * It seems that Microsoft hacked DOS to support non-US 61 * characters after the 0xE5 character was already in use to 62 * mark deleted files. 63 */ 64 if ((res == walk) && (c == 0xE5)) 65 c = 0x05; 66 if (c == '.') 67 break; 68 space = (c == ' '); 69 *walk = (!opts->nocase && c >= 'a' && c <= 'z') ? c - 32 : c; 70 } 71 if (space) 72 return -EINVAL; 73 if (opts->name_check == 's' && len && c != '.') { 74 c = *name++; 75 len--; 76 if (c != '.') 77 return -EINVAL; 78 } 79 while (c != '.' && len--) 80 c = *name++; 81 if (c == '.') { 82 while (walk - res < 8) 83 *walk++ = ' '; 84 while (len > 0 && walk - res < MSDOS_NAME) { 85 c = *name++; 86 len--; 87 if (opts->name_check != 'r' && strchr(bad_chars, c)) 88 return -EINVAL; 89 if (opts->name_check == 's' && 90 strchr(bad_if_strict, c)) 91 return -EINVAL; 92 if (c < ' ' || c == ':' || c == '\\') 93 return -EINVAL; 94 if (c == '.') { 95 if (opts->name_check == 's') 96 return -EINVAL; 97 break; 98 } 99 if (c >= 'A' && c <= 'Z' && opts->name_check == 's') 100 return -EINVAL; 101 space = c == ' '; 102 if (!opts->nocase && c >= 'a' && c <= 'z') 103 *walk++ = c - 32; 104 else 105 *walk++ = c; 106 } 107 if (space) 108 return -EINVAL; 109 if (opts->name_check == 's' && len) 110 return -EINVAL; 111 } 112 while (walk - res < MSDOS_NAME) 113 *walk++ = ' '; 114 115 return 0; 116 } 117 118 /***** Locates a directory entry. Uses unformatted name. */ 119 static int msdos_find(struct inode *dir, const unsigned char *name, int len, 120 struct fat_slot_info *sinfo) 121 { 122 struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb); 123 unsigned char msdos_name[MSDOS_NAME]; 124 int err; 125 126 err = msdos_format_name(name, len, msdos_name, &sbi->options); 127 if (err) 128 return -ENOENT; 129 130 err = fat_scan(dir, msdos_name, sinfo); 131 if (!err && sbi->options.dotsOK) { 132 if (name[0] == '.') { 133 if (!(sinfo->de->attr & ATTR_HIDDEN)) 134 err = -ENOENT; 135 } else { 136 if (sinfo->de->attr & ATTR_HIDDEN) 137 err = -ENOENT; 138 } 139 if (err) 140 brelse(sinfo->bh); 141 } 142 return err; 143 } 144 145 /* 146 * Compute the hash for the msdos name corresponding to the dentry. 147 * Note: if the name is invalid, we leave the hash code unchanged so 148 * that the existing dentry can be used. The msdos fs routines will 149 * return ENOENT or EINVAL as appropriate. 150 */ 151 static int msdos_hash(const struct dentry *dentry, const struct inode *inode, 152 struct qstr *qstr) 153 { 154 struct fat_mount_options *options = &MSDOS_SB(dentry->d_sb)->options; 155 unsigned char msdos_name[MSDOS_NAME]; 156 int error; 157 158 error = msdos_format_name(qstr->name, qstr->len, msdos_name, options); 159 if (!error) 160 qstr->hash = full_name_hash(msdos_name, MSDOS_NAME); 161 return 0; 162 } 163 164 /* 165 * Compare two msdos names. If either of the names are invalid, 166 * we fall back to doing the standard name comparison. 167 */ 168 static int msdos_cmp(const struct dentry *parent, const struct inode *pinode, 169 const struct dentry *dentry, const struct inode *inode, 170 unsigned int len, const char *str, const struct qstr *name) 171 { 172 struct fat_mount_options *options = &MSDOS_SB(parent->d_sb)->options; 173 unsigned char a_msdos_name[MSDOS_NAME], b_msdos_name[MSDOS_NAME]; 174 int error; 175 176 error = msdos_format_name(name->name, name->len, a_msdos_name, options); 177 if (error) 178 goto old_compare; 179 error = msdos_format_name(str, len, b_msdos_name, options); 180 if (error) 181 goto old_compare; 182 error = memcmp(a_msdos_name, b_msdos_name, MSDOS_NAME); 183 out: 184 return error; 185 186 old_compare: 187 error = 1; 188 if (name->len == len) 189 error = memcmp(name->name, str, len); 190 goto out; 191 } 192 193 static const struct dentry_operations msdos_dentry_operations = { 194 .d_hash = msdos_hash, 195 .d_compare = msdos_cmp, 196 }; 197 198 /* 199 * AV. Wrappers for FAT sb operations. Is it wise? 200 */ 201 202 /***** Get inode using directory and name */ 203 static struct dentry *msdos_lookup(struct inode *dir, struct dentry *dentry, 204 unsigned int flags) 205 { 206 struct super_block *sb = dir->i_sb; 207 struct fat_slot_info sinfo; 208 struct inode *inode; 209 int err; 210 211 lock_super(sb); 212 err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 213 switch (err) { 214 case -ENOENT: 215 inode = NULL; 216 break; 217 case 0: 218 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 219 brelse(sinfo.bh); 220 break; 221 default: 222 inode = ERR_PTR(err); 223 } 224 unlock_super(sb); 225 return d_splice_alias(inode, dentry); 226 } 227 228 /***** Creates a directory entry (name is already formatted). */ 229 static int msdos_add_entry(struct inode *dir, const unsigned char *name, 230 int is_dir, int is_hid, int cluster, 231 struct timespec *ts, struct fat_slot_info *sinfo) 232 { 233 struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb); 234 struct msdos_dir_entry de; 235 __le16 time, date; 236 int err; 237 238 memcpy(de.name, name, MSDOS_NAME); 239 de.attr = is_dir ? ATTR_DIR : ATTR_ARCH; 240 if (is_hid) 241 de.attr |= ATTR_HIDDEN; 242 de.lcase = 0; 243 fat_time_unix2fat(sbi, ts, &time, &date, NULL); 244 de.cdate = de.adate = 0; 245 de.ctime = 0; 246 de.ctime_cs = 0; 247 de.time = time; 248 de.date = date; 249 fat_set_start(&de, cluster); 250 de.size = 0; 251 252 err = fat_add_entries(dir, &de, 1, sinfo); 253 if (err) 254 return err; 255 256 dir->i_ctime = dir->i_mtime = *ts; 257 if (IS_DIRSYNC(dir)) 258 (void)fat_sync_inode(dir); 259 else 260 mark_inode_dirty(dir); 261 262 return 0; 263 } 264 265 /***** Create a file */ 266 static int msdos_create(struct inode *dir, struct dentry *dentry, umode_t mode, 267 bool excl) 268 { 269 struct super_block *sb = dir->i_sb; 270 struct inode *inode = NULL; 271 struct fat_slot_info sinfo; 272 struct timespec ts; 273 unsigned char msdos_name[MSDOS_NAME]; 274 int err, is_hid; 275 276 lock_super(sb); 277 278 err = msdos_format_name(dentry->d_name.name, dentry->d_name.len, 279 msdos_name, &MSDOS_SB(sb)->options); 280 if (err) 281 goto out; 282 is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.'); 283 /* Have to do it due to foo vs. .foo conflicts */ 284 if (!fat_scan(dir, msdos_name, &sinfo)) { 285 brelse(sinfo.bh); 286 err = -EINVAL; 287 goto out; 288 } 289 290 ts = CURRENT_TIME_SEC; 291 err = msdos_add_entry(dir, msdos_name, 0, is_hid, 0, &ts, &sinfo); 292 if (err) 293 goto out; 294 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 295 brelse(sinfo.bh); 296 if (IS_ERR(inode)) { 297 err = PTR_ERR(inode); 298 goto out; 299 } 300 inode->i_mtime = inode->i_atime = inode->i_ctime = ts; 301 /* timestamp is already written, so mark_inode_dirty() is unneeded. */ 302 303 d_instantiate(dentry, inode); 304 out: 305 unlock_super(sb); 306 if (!err) 307 err = fat_flush_inodes(sb, dir, inode); 308 return err; 309 } 310 311 /***** Remove a directory */ 312 static int msdos_rmdir(struct inode *dir, struct dentry *dentry) 313 { 314 struct super_block *sb = dir->i_sb; 315 struct inode *inode = dentry->d_inode; 316 struct fat_slot_info sinfo; 317 int err; 318 319 lock_super(sb); 320 /* 321 * Check whether the directory is not in use, then check 322 * whether it is empty. 323 */ 324 err = fat_dir_empty(inode); 325 if (err) 326 goto out; 327 err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 328 if (err) 329 goto out; 330 331 err = fat_remove_entries(dir, &sinfo); /* and releases bh */ 332 if (err) 333 goto out; 334 drop_nlink(dir); 335 336 clear_nlink(inode); 337 inode->i_ctime = CURRENT_TIME_SEC; 338 fat_detach(inode); 339 out: 340 unlock_super(sb); 341 if (!err) 342 err = fat_flush_inodes(sb, dir, inode); 343 344 return err; 345 } 346 347 /***** Make a directory */ 348 static int msdos_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 349 { 350 struct super_block *sb = dir->i_sb; 351 struct fat_slot_info sinfo; 352 struct inode *inode; 353 unsigned char msdos_name[MSDOS_NAME]; 354 struct timespec ts; 355 int err, is_hid, cluster; 356 357 lock_super(sb); 358 359 err = msdos_format_name(dentry->d_name.name, dentry->d_name.len, 360 msdos_name, &MSDOS_SB(sb)->options); 361 if (err) 362 goto out; 363 is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.'); 364 /* foo vs .foo situation */ 365 if (!fat_scan(dir, msdos_name, &sinfo)) { 366 brelse(sinfo.bh); 367 err = -EINVAL; 368 goto out; 369 } 370 371 ts = CURRENT_TIME_SEC; 372 cluster = fat_alloc_new_dir(dir, &ts); 373 if (cluster < 0) { 374 err = cluster; 375 goto out; 376 } 377 err = msdos_add_entry(dir, msdos_name, 1, is_hid, cluster, &ts, &sinfo); 378 if (err) 379 goto out_free; 380 inc_nlink(dir); 381 382 inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos); 383 brelse(sinfo.bh); 384 if (IS_ERR(inode)) { 385 err = PTR_ERR(inode); 386 /* the directory was completed, just return a error */ 387 goto out; 388 } 389 set_nlink(inode, 2); 390 inode->i_mtime = inode->i_atime = inode->i_ctime = ts; 391 /* timestamp is already written, so mark_inode_dirty() is unneeded. */ 392 393 d_instantiate(dentry, inode); 394 395 unlock_super(sb); 396 fat_flush_inodes(sb, dir, inode); 397 return 0; 398 399 out_free: 400 fat_free_clusters(dir, cluster); 401 out: 402 unlock_super(sb); 403 return err; 404 } 405 406 /***** Unlink a file */ 407 static int msdos_unlink(struct inode *dir, struct dentry *dentry) 408 { 409 struct inode *inode = dentry->d_inode; 410 struct super_block *sb = inode->i_sb; 411 struct fat_slot_info sinfo; 412 int err; 413 414 lock_super(sb); 415 err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo); 416 if (err) 417 goto out; 418 419 err = fat_remove_entries(dir, &sinfo); /* and releases bh */ 420 if (err) 421 goto out; 422 clear_nlink(inode); 423 inode->i_ctime = CURRENT_TIME_SEC; 424 fat_detach(inode); 425 out: 426 unlock_super(sb); 427 if (!err) 428 err = fat_flush_inodes(sb, dir, inode); 429 430 return err; 431 } 432 433 static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name, 434 struct dentry *old_dentry, 435 struct inode *new_dir, unsigned char *new_name, 436 struct dentry *new_dentry, int is_hid) 437 { 438 struct buffer_head *dotdot_bh; 439 struct msdos_dir_entry *dotdot_de; 440 struct inode *old_inode, *new_inode; 441 struct fat_slot_info old_sinfo, sinfo; 442 struct timespec ts; 443 loff_t new_i_pos; 444 int err, old_attrs, is_dir, update_dotdot, corrupt = 0; 445 446 old_sinfo.bh = sinfo.bh = dotdot_bh = NULL; 447 old_inode = old_dentry->d_inode; 448 new_inode = new_dentry->d_inode; 449 450 err = fat_scan(old_dir, old_name, &old_sinfo); 451 if (err) { 452 err = -EIO; 453 goto out; 454 } 455 456 is_dir = S_ISDIR(old_inode->i_mode); 457 update_dotdot = (is_dir && old_dir != new_dir); 458 if (update_dotdot) { 459 if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de)) { 460 err = -EIO; 461 goto out; 462 } 463 } 464 465 old_attrs = MSDOS_I(old_inode)->i_attrs; 466 err = fat_scan(new_dir, new_name, &sinfo); 467 if (!err) { 468 if (!new_inode) { 469 /* "foo" -> ".foo" case. just change the ATTR_HIDDEN */ 470 if (sinfo.de != old_sinfo.de) { 471 err = -EINVAL; 472 goto out; 473 } 474 if (is_hid) 475 MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN; 476 else 477 MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN; 478 if (IS_DIRSYNC(old_dir)) { 479 err = fat_sync_inode(old_inode); 480 if (err) { 481 MSDOS_I(old_inode)->i_attrs = old_attrs; 482 goto out; 483 } 484 } else 485 mark_inode_dirty(old_inode); 486 487 old_dir->i_version++; 488 old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME_SEC; 489 if (IS_DIRSYNC(old_dir)) 490 (void)fat_sync_inode(old_dir); 491 else 492 mark_inode_dirty(old_dir); 493 goto out; 494 } 495 } 496 497 ts = CURRENT_TIME_SEC; 498 if (new_inode) { 499 if (err) 500 goto out; 501 if (is_dir) { 502 err = fat_dir_empty(new_inode); 503 if (err) 504 goto out; 505 } 506 new_i_pos = MSDOS_I(new_inode)->i_pos; 507 fat_detach(new_inode); 508 } else { 509 err = msdos_add_entry(new_dir, new_name, is_dir, is_hid, 0, 510 &ts, &sinfo); 511 if (err) 512 goto out; 513 new_i_pos = sinfo.i_pos; 514 } 515 new_dir->i_version++; 516 517 fat_detach(old_inode); 518 fat_attach(old_inode, new_i_pos); 519 if (is_hid) 520 MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN; 521 else 522 MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN; 523 if (IS_DIRSYNC(new_dir)) { 524 err = fat_sync_inode(old_inode); 525 if (err) 526 goto error_inode; 527 } else 528 mark_inode_dirty(old_inode); 529 530 if (update_dotdot) { 531 fat_set_start(dotdot_de, MSDOS_I(new_dir)->i_logstart); 532 mark_buffer_dirty_inode(dotdot_bh, old_inode); 533 if (IS_DIRSYNC(new_dir)) { 534 err = sync_dirty_buffer(dotdot_bh); 535 if (err) 536 goto error_dotdot; 537 } 538 drop_nlink(old_dir); 539 if (!new_inode) 540 inc_nlink(new_dir); 541 } 542 543 err = fat_remove_entries(old_dir, &old_sinfo); /* and releases bh */ 544 old_sinfo.bh = NULL; 545 if (err) 546 goto error_dotdot; 547 old_dir->i_version++; 548 old_dir->i_ctime = old_dir->i_mtime = ts; 549 if (IS_DIRSYNC(old_dir)) 550 (void)fat_sync_inode(old_dir); 551 else 552 mark_inode_dirty(old_dir); 553 554 if (new_inode) { 555 drop_nlink(new_inode); 556 if (is_dir) 557 drop_nlink(new_inode); 558 new_inode->i_ctime = ts; 559 } 560 out: 561 brelse(sinfo.bh); 562 brelse(dotdot_bh); 563 brelse(old_sinfo.bh); 564 return err; 565 566 error_dotdot: 567 /* data cluster is shared, serious corruption */ 568 corrupt = 1; 569 570 if (update_dotdot) { 571 fat_set_start(dotdot_de, MSDOS_I(old_dir)->i_logstart); 572 mark_buffer_dirty_inode(dotdot_bh, old_inode); 573 corrupt |= sync_dirty_buffer(dotdot_bh); 574 } 575 error_inode: 576 fat_detach(old_inode); 577 fat_attach(old_inode, old_sinfo.i_pos); 578 MSDOS_I(old_inode)->i_attrs = old_attrs; 579 if (new_inode) { 580 fat_attach(new_inode, new_i_pos); 581 if (corrupt) 582 corrupt |= fat_sync_inode(new_inode); 583 } else { 584 /* 585 * If new entry was not sharing the data cluster, it 586 * shouldn't be serious corruption. 587 */ 588 int err2 = fat_remove_entries(new_dir, &sinfo); 589 if (corrupt) 590 corrupt |= err2; 591 sinfo.bh = NULL; 592 } 593 if (corrupt < 0) { 594 fat_fs_error(new_dir->i_sb, 595 "%s: Filesystem corrupted (i_pos %lld)", 596 __func__, sinfo.i_pos); 597 } 598 goto out; 599 } 600 601 /***** Rename, a wrapper for rename_same_dir & rename_diff_dir */ 602 static int msdos_rename(struct inode *old_dir, struct dentry *old_dentry, 603 struct inode *new_dir, struct dentry *new_dentry) 604 { 605 struct super_block *sb = old_dir->i_sb; 606 unsigned char old_msdos_name[MSDOS_NAME], new_msdos_name[MSDOS_NAME]; 607 int err, is_hid; 608 609 lock_super(sb); 610 611 err = msdos_format_name(old_dentry->d_name.name, 612 old_dentry->d_name.len, old_msdos_name, 613 &MSDOS_SB(old_dir->i_sb)->options); 614 if (err) 615 goto out; 616 err = msdos_format_name(new_dentry->d_name.name, 617 new_dentry->d_name.len, new_msdos_name, 618 &MSDOS_SB(new_dir->i_sb)->options); 619 if (err) 620 goto out; 621 622 is_hid = 623 (new_dentry->d_name.name[0] == '.') && (new_msdos_name[0] != '.'); 624 625 err = do_msdos_rename(old_dir, old_msdos_name, old_dentry, 626 new_dir, new_msdos_name, new_dentry, is_hid); 627 out: 628 unlock_super(sb); 629 if (!err) 630 err = fat_flush_inodes(sb, old_dir, new_dir); 631 return err; 632 } 633 634 static const struct inode_operations msdos_dir_inode_operations = { 635 .create = msdos_create, 636 .lookup = msdos_lookup, 637 .unlink = msdos_unlink, 638 .mkdir = msdos_mkdir, 639 .rmdir = msdos_rmdir, 640 .rename = msdos_rename, 641 .setattr = fat_setattr, 642 .getattr = fat_getattr, 643 }; 644 645 static void setup(struct super_block *sb) 646 { 647 MSDOS_SB(sb)->dir_ops = &msdos_dir_inode_operations; 648 sb->s_d_op = &msdos_dentry_operations; 649 sb->s_flags |= MS_NOATIME; 650 } 651 652 static int msdos_fill_super(struct super_block *sb, void *data, int silent) 653 { 654 return fat_fill_super(sb, data, silent, 0, setup); 655 } 656 657 static struct dentry *msdos_mount(struct file_system_type *fs_type, 658 int flags, const char *dev_name, 659 void *data) 660 { 661 return mount_bdev(fs_type, flags, dev_name, data, msdos_fill_super); 662 } 663 664 static struct file_system_type msdos_fs_type = { 665 .owner = THIS_MODULE, 666 .name = "msdos", 667 .mount = msdos_mount, 668 .kill_sb = kill_block_super, 669 .fs_flags = FS_REQUIRES_DEV, 670 }; 671 672 static int __init init_msdos_fs(void) 673 { 674 return register_filesystem(&msdos_fs_type); 675 } 676 677 static void __exit exit_msdos_fs(void) 678 { 679 unregister_filesystem(&msdos_fs_type); 680 } 681 682 MODULE_LICENSE("GPL"); 683 MODULE_AUTHOR("Werner Almesberger"); 684 MODULE_DESCRIPTION("MS-DOS filesystem support"); 685 686 module_init(init_msdos_fs) 687 module_exit(exit_msdos_fs) 688